纳米强韧化界面层对碳纤维复合材料界面性能与疲劳特性的协同强化机制

Carbon fiber reinforced composites have been used as one of key materials in the national defense and civil field. The improvement of interfacial bonding strength increases the interface properties of composites but decreases anti-fatigue ability of composites. As a result, the synergetic enhancement of interfacial and anti-fatigue properties has been a great challenge for performance-enhancing design of composites. We will coat the sizing containing the etched graphene nanosheets on the surface of carbon fibers, and combine the carbon fibers and epoxy to prepare the multi-composites. It is expected that the graphene nanosheets absorbed on fiber surface would diffuse into the matrix, the interface layer with gradient modulus is formed between fiber and matrix, and the interfacial and anti-fatigue properties are both improved, which results from reducing the interfacial stress concentration. In this research, the structure of interface layer will be designed, the formation mechanisms and structural adjustment methods of interface layer will be investigated and the relations among interlayer microstructure, carbon fiber/epoxy interface properties and composite fatigue characteristics will be studied to reveal the effect mechanisms of interlayer structure on the fatigue behavior. This project would contribute theoretic basis and experimental base to the use of graphene nanosheets in structural composites and thus be of significance for the improvement of composite application and safety reliability.

碳纤维增强树脂基复合材料已成为国防及民用领域的关键材料。本项目针对“强界面结合提高复合材料界面性能的同时削弱抗疲劳特性”的问题，以碳纤维/环氧树脂体系为研究对象，将小粒径、面内刻蚀和酸酐功能化的石墨烯纳米片引入环氧杂化浆料，再将涂覆该浆料的碳纤维与环氧树脂复合，使碳纤维表面物理吸附的石墨烯扩散进入纤维周围的树脂微区，在纤维与基体之间构筑模量呈梯度变化的界面过渡层，从减少界面应力集中的角度实现复合材料界面性能和抗疲劳特性的协同提高。采用有限元方法设计界面层的基本性质，并结合过渡层理论调控界面层结构，研究界面层的形成机理及其精细结构调控方法，探讨界面层微观结构与碳纤维/环氧界面性能、抗疲劳性能之间的构效关系，揭示界面层对复合材料界面性能与疲劳特性的协同强化机制。项目将为多尺度、多层次高性能复合材料的结构设计提供理论依据和实验基础，对于提升碳纤维增强树脂基复合材料的应用性和可靠性具有重要意义。

碳纤维增强树脂基复合材料在石油化工、航空航天等领域具有广泛的应用前景。本项目针对碳纤维增强树脂基复合材料在界面和抗疲劳协同改性方面存在的问题，以碳纤维/环氧树脂体系为研究对象，通过引入低维碳纳米材料增强的界面过渡层，实现了碳纤维增环氧树脂复合材料的界面、力学与抗疲劳性能的同步提升。项目首先采用γ射线辐照改性技术对碳纤维表面活性及力学性能进行了优化，实现了碳纤维表面活性与力学性能的协同提高；借助等离子体处理以及原位聚合等手段对石墨烯纳米片、碳纳米管进行了功能化处理，并将其与聚合物复合成型，探索了石墨烯的结构形貌对其分散性以及聚合物力学和功能性能的影响；在前两者研究成果的基础上，申请人将功能化碳纳米材料(石墨烯、碳纳米管)组装到碳纤维表面，制备了碳纳米材料─碳纤维/环氧树脂多尺度复合材料，使低维碳纳米材料在界面层内沿纤维径向呈梯度分布，在纤维/树脂界面微区引入了梯度界面层。在对比了二者改性效果基础上，优选了功能化碳纳米管作为改性剂，重点分析了碳纳米管的含量、分布对碳纤维复合材料界面性能及抗疲劳特性的影响，并通过超声影像技术对疲劳过程的裂纹扩展与分布进行了研究，揭示了碳纳米管在碳纤维表面的组装对碳纤维增强树脂复合材料界面及抗疲劳特性的影响机制。